US officials confirmed on Wednesday that Iran's nuclear ambitions were discussed by President George Bush and Israeli Prime Minister Ariel Sharon at their Texas summit on Monday.
The New York Times said Sharon spread out photos of Iranian nuclear sites and cited Israeli intelligence that showed Iran was near "a point of no return" in developing the know-how to produce a bomb.
State Department spokesman Richard Boucher said the international community was concerned about Iran's intentions, but US intelligence suggested Tehran still had a ways to go in developing nuclear weapons.
"Our intelligence community has used in the past an estimate that said that Iran was not likely to acquire a nuclear weapon before the beginning of the next decade. That remains the case," he said.
"But I don't think there's any dispute that Iran should not have the capabilities, the programmes that have been used and that can be used as cover for nuclear weapons development."
Estimates of Iran's nuclear arms capability have varied over the years. In 1994, then CIA Director James Woolsey said the belief was that Iran was eight to 10 years away from building such weapons.
Sharon discussed Iran's nuclear
programme with Bush
The reliability of intelligence has come into question.
A presidential commission reported two weeks ago that US agencies knew "disturbingly little" about the weapons programmes of Iran and other potential threats.
The US says that oil-rich Iran is using its civilian nuclear programme to cover up a quest for atomic weapons. Tehran denies the accusation.
In his presentation to Bush, Sharon reportedly expressed frustration that efforts by France, Germany and Britain to wean Iran off its nuclear ambitions through trade, security and technology incentives were stalling.
But White House spokesman Scott McClellan said that Bush "talked about the importance of supporting the European efforts".
"What we are doing is continuing to support the Europeans in their efforts to get Iran to abandon their nuclear weapon ambitions, and the president talked about the diplomatic efforts going on by the Europeans," McClellan said.
Boucher also reaffirmed US opposition to suggestions that the Iranians be permitted to maintain a limited level of uranium-enrichment activity, as some Europeans were reportedly proposing.
"We all have a shared concern and a shared goal, our shared goal is to make sure Iran does not develop a nuclear weapon. That would be a very destabilising factor in the region
White House spokesman
"The position of the United States and I think many other members of the international community has been and continues to be that the suspension of enrichment activity needs to be made permanent," he said.
McClellan declined to discuss the reported Israeli photographs or whether Bush had told Sharon that Israel should not take matters into its own hands, echoing Vice President Dick Cheney's warning in January.
"We all have a shared concern and a shared goal. Our shared goal is to make sure Iran does not develop a nuclear weapon. That would be a very destabilising factor in the region," said the spokesman.
"We continue to support those (European) diplomatic efforts to resolve this in a peaceful manner," McClellan said.
On Thursday, Secretary of State Condoleezza Rice told The Wall Street that the US will decide this summer whether to pursue a tougher stand on Iran's nuclear programme.
Rice said Washington has faith in European-led negotiations aimed at ensuring that Iran's nuclear programme remains non-military and that what matters most is "a unity of purpose" among all the nations involved.
Rice, however, told the newspaper the Israelis had provided "no new revelation" on Iran's alleged nuclear programme.